JP3823528B2 - Exhaust gas purification material and exhaust gas purification apparatus using the same - Google Patents
Exhaust gas purification material and exhaust gas purification apparatus using the same Download PDFInfo
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- JP3823528B2 JP3823528B2 JP11044298A JP11044298A JP3823528B2 JP 3823528 B2 JP3823528 B2 JP 3823528B2 JP 11044298 A JP11044298 A JP 11044298A JP 11044298 A JP11044298 A JP 11044298A JP 3823528 B2 JP3823528 B2 JP 3823528B2
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- Exhaust Gas Treatment By Means Of Catalyst (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、ディ−ゼル機関などの燃焼機関や産業排ガス中に含有される炭化水素や可燃性炭素微粒子などの粒子状物質（パティキュレート）を除去する排ガス浄化材及びこの排ガス浄化材を用いた排ガス浄化装置に関する。
【０００２】
【従来の技術】
ディ−ゼルエンジンの排ガス中のパティキュレートはその粒子径のほとんどが１ミクロン以下であり、大気中に浮遊しやすく呼吸により人体に取り込まれやすい。しかも発ガン性物質を含んでいることから、排出の規制は今後更に厳しくなることが予測される。
【０００３】
従来、これらの微粒子状物質の除去方法としては、大別すると以下の２つの方法がある。
【０００４】
（１）片端閉じのセラミックハニカム、セラミックフォーム、金属発泡体などの耐熱性のガスフィルターを用いて排ガス中の微粒子を捕集し、背圧が上昇すれば電気ヒーターなどで堆積した微粒子を燃焼させフィルターを再生する方法。
【０００５】
（２）触媒を用いて微粒子を触媒作用により燃焼反応を行わせ、ヒーターなどを要せず排ガス中で排ガスの温度で燃焼再生を行う方法。
【０００６】
しかしながら、前記（１）の方法ではパティキュレートの燃焼温度が高温であり、捕集したパティキュレートを燃焼除去し、フィルターを再生するために多量のエネルギーが必要となる。さらに高温域での燃焼とその反応熱によりフィルターの溶損や割れを生じる。また、特殊な装置を必要とするために浄化装置としての大型化、高コスト化が問題となる。
【０００７】
一方、前記（２）の方式では排ガス処理温度域で触媒の作用で燃焼除去させるため、特殊な装置を必要とせず小型化、低コスト化の浄化装置となるが、排ガス温度全域で浄化が可能となる触媒は開発されていない。
【０００８】
【発明が解決しようとする課題】
触媒を担持する耐熱性の構造体としては、ガソリン車で一般に使われているハニカム構造体のものや、パティキュレートの捕集を目的としたハニカム構造の個々のセルを一個毎に閉塞させた片端閉のハニカム構造のフィルターがある。
【０００９】
しかしながら、ハニカム構造の構造体では排ガスの通路が直線的であり、その通路を数ｍ〜数十ｍ以上の速度で通過する固体状のパティキュレートは、排ガスの流れの垂直方向（ハニカム壁方向）の速度成分は気体分子に比べて著しく小さい。そのため、通路壁にコーティングした触媒とは接触し難く、浄化反応が起こりにくい。一方、セルの片端を閉塞させた片端閉の捕集を目的としたハニカム構造では、セル通路を構成する壁面によってパティキュレートが排ガス中から濾過、捕集される。このため壁面にコーティングした触媒との接触性は良好である。
【００１０】
ところが、この場合、触媒の活性が十分に作用しない低い排ガス温度域での運転が続くと、パティキュレートが完全には浄化されずにセル壁面上のパティキュレートの堆積量が増し、背圧が大きくなり、長時間使用できないなどの問題が生じる。
【００１１】
本発明は、ディーゼル機関からのパティキュレートに対して燃焼性に優れ低負荷、低回転のような極端に排ガス温度が低く、触媒作用が十分発現しない低温度域でも、パティキュレートのフィルターへの堆積による圧力損失が問題とならない長時間安定して使用することができる排ガス浄化材及びこれを用いた排ガス浄化装置を提供することを目的とする。
【００１２】
【課題を解決するための手段】
本発明は、上記目的を達成するために、内部連続通気孔を有する３次元網目構造体の表面に凹凸の耐熱性無機材料部が得られるように、３次元構造体に形成する材料が耐熱性無機材料のゾルと耐熱性無機材料の粉末からなり、前記耐熱性無機材料のゾルの粒子径が５ｎｍよりも大きく且つ１６０ｎｍよりも小さく、前記耐熱性無機材料の酸化物粒子の粒子径が０．５μｍよりも大きくて９μｍよりも小さいものとしたもので、３次元構造体の表面に凹凸の耐熱性無機材料部が得られる。これにより、混合する耐熱性無機材料の粒子が脱離することなく安定して３次元構造体表面に形成され、この上に付着させた触媒が３次元網目構造体との反応により劣化することを抑制でき、更に触媒とパティキュレートとの接触性が向上し、３次元構造体通過中に効率よくパティキュレートの燃焼が可能となる。
【００１３】
３次元の網目構造としては構造内に連続通気空間を有し、その空間の数が１平方インチ当たり５から３０個で好ましくは１０から２０個のものである。さらに好ましくは３次元網目構造体の排ガス流入出面への垂線が排ガス流れ方向に対して鋭角あるいは鈍角をなすものである。また、ハニカム構造体としては１平方インチ当たり２００〜５００個のものである。３次元網目構造体、或いはハニカム構造体の材料としてはコージェライト（２ＭｇＯ・５ＳｉＯ2・２Ａｌ2Ｏ3）、ムライト（Ａｌ2Ｏ3・３ＳｉＯ2）、アルミナ（Ａｌ2Ｏ3）、シリカ（ＳｉＯ2）、チタニア（ＴｉＯ2）、ジルコニア（ＺｒＯ2）、シリカ−アルミナ、アルミナ−ジルコニア、アルミナ−チタニア、シリカ−チタニア、シリカ−ジルコニア、チタニア−ジルコニアなどのセラミックスと、ＳＵＳ３０１Ｓ、インコネル（インコネルＸ、インコネルＷなど）などの金属材料が挙げられるが、これに限定されるものではない。
【００１４】
更に、この３次元網目構造体或いはハニカム構造体に無機質コート層を形成する。無機質コート層とは３次元網目構造体上にコートされる高比表面積の多孔質体である。無機質コート層の材料としては通常、アルミナ、シリカ、チタニア、ジルコニア、シリカ−アルミナ、アルミナ−ジルコニア、アルミナ−チタニアなどのセラミックス等が好適に用いられるが、これに限定されるものではない。
【００１５】
３次元網目構造体或いはハニカム構造体上へ無機質コート層を担持させる方法としては、ゾル−ゲル法や、スラリー法などが挙げられる。
【００１６】
ゾル−ゲル法とは、無機質コート層を構成する金属元素の有機塩（アルコキシドなど）を含む溶液に酸（塩酸、酢酸など）を加えて溶液のｐＨを調製した後、この溶液に３次元構造体或いはハニカム構造体を含浸して無機質コート層を構成する金属元素を含む溶液をコーティングし、次いで３次元網目構造体或いはハニカム構造体にコーティングされた溶液と水蒸気とを接触させ加水分解反応によりゾル化させ、さらにゲル化を行った後に焼成するものである。
【００１７】
スラリー法とは、無機質コート層の原料粉体をあらかじめ分散剤（ポリカルボン酸塩など）を溶解した水溶液に投入し、この水溶液中の原料粉体をボールミルなどにて解粒、混合を行うことによりスラリーを調製した後、このスラリーに３次元網目構造体或いはハニカム構造体を含浸してスラリーをコーティングした後に焼成するものである。これらが担持の一般的方法として挙げられるが、これに限定されるものではない。
【００１８】
但し、３次元網目構造体に形成される無機質部としてはＺｒＯ2やＴｉＯ2、ＳｉＯ2などがあげられ、特にＳｉＯ2のゾルが好ましく、また、ゾルの粒子径は５ｎｍよりも大きく、且つ１６０ｎｍよりも小さいものが好ましい。当該ゾルに耐熱性の粉末を混合したものであり、その粉末の粒子径が０．５μｍよりも大きく、且つ９μｍよりも小さいものが好ましい。
【００１９】
これら構造体に付着せしめる触媒材料としては、ＩＵＰＡＣ分類による１ａ族元素の塩と５ａ族元素と１ｂ族元素からなるもの、及び、１ａ族元素の塩と５ａ族元素と１ｂ族元素と６ａ族、７ａ族、８ａ族の中の少なくとも１種からなるもの、があげられる。
【００２０】
上記触媒は以下の方法により作製する。すなわち、各構成元素の酸化物、水酸化物、炭酸塩、酢酸塩、硝酸塩、シュウ塩、塩化物などを所定の割合で混合する。混合する方法としては、各材料を固体状態で混合する方法、各金属塩の混合水溶液を調製した後、溶媒を蒸発させ、金属塩を固化させる方法、各金属塩の混合水溶液を調製した後、アンモニア水などを加え加水分解する方法、各金属塩の混合水溶液を調製した後、適量のクエン酸、リンゴ酸などの多価の有機カルボン酸を添加し、溶媒を蒸発させるか、溶液のｐＨ調整することにより固化させる方法を用いることができる。このようにして調製した混合物を焼成することにより所定の触媒が得られる。また、触媒の各構成元素を別々に上記と同等の方法で、作製することも可能である。
【００２１】
この構成により、触媒と排出されてくるパティキュレートとの接触が十分に保たれ、高い活性を有する本触媒によりパティキュレートの浄化反応が進行する。
【００２２】
また、排ガス温度が極端に低い場合には、本触媒の作用により排出パティキュレートの一部は燃焼され、未燃焼のパティキュレートは系外に排出される。これにより触媒の作用によりパティキュレートを１００％燃焼除去できない排ガス温度域においてもフィルター内にパティキュレートが堆積し差圧が上昇することがなく、連続的に安定してパティキュレートの燃焼除去が可能となる。
【００２３】
また、上記無機構造体の排ガス入り口側に、ＩＵＰＡＣ分類による１ａ族元素の塩と５ａ族元素と１ｂ族元素からなる触媒、または１ａ族元素の塩と５ａ族元素と１ｂ族元素と６ａ族、７ａ族、８ａ族の中の少なくとも１種からなる触媒を付着させた構成とし、排ガス出口側に白金族を付着させた構成とすることによりパティキュレートに加えて、ＣＯ、ＨＣの浄化も可能となる。
【００２４】
【発明の実施の形態】
本発明の請求項１に記載の発明は、３次元構造体に形成する材料が耐熱性無機材料のゾルと耐熱性無機材料の粉末からなり、粒子径が５ｎｍよりも大きく且つ１６０ｎｍよりも小さい耐熱性無機材料のゾルと混合する耐熱性無機材料の粒子の粒子径が０．５μｍよりも大きく且つ９μｍよりも小さいものであり、これにより、３次元構造体の表面に凹凸の耐熱性無機材料部が得られ、混合する耐熱性無機材料の粒子が脱離することなく安定して３次元構造体表面に形成される。これにより、この上に付着させた触媒が３次元網目構造体との反応により劣化することが抑制でき、更に触媒とパティキュレートとの接触性が向上し、３次元構造体通過中に効率よく長時間安定してパティキュレートの燃焼が可能となる。
【００２５】
請求項２の発明は３次元構造体の表面に形成する耐熱性無機酸化物がＳｉＯ2であるものである。これにより、この上に形成した触媒が３次元網目構造体との反応により劣化することが抑制でき、更に触媒とパティキュレートとの接触性が向上し、３次元構造体通過中に効率よく長時間安定してパティキュレートの燃焼が可能となる。
【００２６】
請求項３の発明は、請求項１または２に記載の排ガス浄化材において３次元網目構造体が請求項２２の発明における３次元構造体であるものであり、初期の差圧が小さく、パティキュレートの堆積が問題とならず、構造体通過中に効率良く長時間安定してパティキュレートの燃焼が可能となるという作用を有する。
【００２７】
請求項４の発明は、請求項１から３のいずれかに記載の排ガス浄化材と、前記排ガス浄化材を収納する容器と、前記容器の一部に形成された排ガス流入口と、前記容器の他側部に形成された排ガス流入口とを備えた排ガス浄化装置であり、装置構成が簡単で排ガス浄化特性に優れた浄化装置が得られるという作用を有する。
【００２８】
請求項５の発明は、請求項４に記載の浄化装置において、前記容器及び／又は前記容器の排ガス流入口とエンジンを接続する接続管の周囲に設置された断熱手段を有するものであり、エンジン燃焼部からの排ガスが触媒部に流入する温度の低下を防止して触媒活性を向上させ得るという作用を有する。
【００２９】
請求項６の発明は、請求項５の発明において、前記容器がエンジンマニホールドに近接して配置されたものであり、エンジン燃焼部からの排ガスが触媒部に流入する温度の低下を防止して触媒活性を向上させることができるという作用を有する。
【００３０】
以下、本発明の実施の形態における排ガス浄化材について説明する。図１は本発明の実施の形態における排ガス浄化装置の構成を示す図であり、図２は排ガス浄化材の他の実施の形態を示す排ガス浄化装置の部分拡大図である。また、図３は本発明の３次元網目構造の形態を示す図である。
【００３１】
図１において、エンジン６に接続した排ガス入口１と排ガス出口２との間にキャン５を形成し、その中に３次元網目状構造体３を組み込み、キャン５をバイパスする流路には差圧計７を配置している。また、図２においては、３次元網目状構造体３の下流側にハニカム構造体４が組み込まれている。
【００３２】
図１及び図２において、３次元網目状構造体３及びハニカム構造体４がそれぞれ内部連続通気空間を形成する３次元構造体であり、これらの３次元網目状構造体３及びハニカム構造体４の表面に耐熱性無機材料及び触媒（白金属元素を含む）が付着させられている。また、キャン５は真空容器であって断熱手段を自身に備えたものであり、エンジン６との接続点部分が本実施の形態におけるマニホールドに相当する。
【００３３】
図３において３次元構造体の排ガス流入出面への垂線が排ガス流れ方向に対して鋭角あるいは鈍角をなしている。
【００３４】
【実施例】
（参考例１〜５）
コージェライトの粉末（粒径：５μｍ）をこの粉末量に対して０．５ｗｔ％となるようにポリカルボン酸アンモニウム塩を溶解させた水溶液に投入した後、ボールミルにて１８時間解粒・混合して、スラリーを調製した。次にこのスラリーに密度、孔径の異なるウレタン製の発泡体を含浸させ、遠心分離器により余剰のスラリーを取り除いた後、１３８０℃で５時間焼成して（表１）に示す特性のものを参考例１〜５としてそれぞれ３次元網目構造体を作製した。
【００３５】
【表１】
また、出発原料として硫酸セシウム、硝酸銅を３次元構造体に対して７ｗｔ％、モル比：Ｃｓ／Ｃｕ＝１／４となるように秤量して蒸留水に溶解させて水溶液を調製した後、前記３次元網目構造体を含浸した後、真空デシケーター内を減圧して３次元網目構造体内の気泡を取り除き、３次元網目構造体の内部までスラリーを浸透させた。次に余分なスラリーを遠心分離器を利用し、振り切って１２０℃で５時間乾燥したのち、９００℃で２時間焼成して触媒を付着した３次元網目構造体を作製した。
【００３７】
（参考例６〜１８）
出発原料として１ａ族元素に硫酸セシウムを用いこれと硝酸銅、酸化硫酸バナジウム、硝酸クロム、酢酸マンガン、酢酸鉄、酢酸コバルト、酢酸ニッケル、７モリブデン酸６アンモニウム４水和物、タングステン酸アンモニウムパラ５水和物を用い各原料を３次元構造体に対して７ｗｔ％、セシウムに対してモル比で１：４になるように秤量し、約４０℃の蒸留水に溶解させて水溶液を作製した。次に内部連続通気空間の数が２３個の前記３次元網目構造体を含浸した後、真空デシケーター内を減圧して３次元網目構造体内の気泡を取り除き、３次元網目構造体の内部までスラリーを浸透させた。次に余分なスラリーを遠心分離器を利用し、振り切って１２０℃で５時間乾燥したのち、９００℃で２時間焼成して触媒を付着した参考例６〜１８の３次元網目構造体を作製した。
【００３８】
（参考例１９〜２０）
ＳｉＯ2、γ−Ａｌ2Ｏ3粉末を用い、３次元網目構造体にたいして１５ｗｔ％になるように秤量し、この粉体に対して０．５ｗｔ％のポリカルボン酸アンモニウム塩を溶解させた水溶液に、接着剤として用いるアルミニウムイソプロポキシトとこれらの粉末を各々投入した後、これをボールミルにて１８時間解粒・混合して、スラリーを調製した。
【００３９】
次に、真空デシケーター内で、得られたスラリーに３次元網目構造体を含浸した後、真空デシケーター内を減圧して３次元網目構造体内の気泡を取り除き、３次元網目構造体の内部までスラリーを浸透させた。次に余分なスラリーを遠心分離器を利用し、振り切って１２０℃で５時間乾燥したのち、９００℃で２時間焼成した。次に参考例６と同様の方法にて所定の触媒を担持した。
【００４０】
（参考例２１）
γ−Ａｌ2Ｏ3の粉末を用い、これに対して０．５ｗｔ％となるようにポリカルボン酸アンモニウム塩を溶解させた水溶液に、更に接着剤としてアルミニウムイソプロポキシトを加えた後、真空デシケーター内で、得られたスラリーに３次元網目構造体を含浸した後、真空デシケーター内を減圧して３次元網目構造体内の気泡を取り除き、３次元網目構造体の内部までスラリーを浸透させた。次に余分なスラリーを遠心分離器を利用し、振り切って１２０℃で５時間乾燥したのち、９００℃で２時間焼成した。
【００４１】
次に参考例６と同じ方法にて所定の触媒スラリーを調製し、３次元網目構造体の片側を含浸させる。含浸した側の３次元網目構造体を遠心分離器の回転の外側になるように設定して回転させて、余剰の触媒スラリーを取り除いて９００℃で２時間焼成した。
【００４２】
次に上記触媒を付着させていない側をγ−Ａｌ2Ｏ3に対して１．５ｗｔ％になるようにヘキサクロロ白金酸を溶解させた溶液に同様に含浸、乾燥を行い６００℃で３時間焼成することにより触媒付着フィルターを調製した。
【００４３】
（参考例２２）
γ−Ａｌ2Ｏ3の粉末を用い、これに対して０．５ｗｔ％となるようにポリカルボン酸アンモニウム塩を溶解させた水溶液に、接着剤として用いるアルミニウムイソプロポキシトとこれらの粉末を各々投入した後、これをボールミルにて１８時間解粒・混合して、スラリーを調製した。
【００４４】
次に、真空デシケーター内で、得られたスラリーにハニカム構造体を含浸した後、真空デシケーター内を減圧してハニカム構造体内の気泡を取り除き、ハニカム構造体の内部までスラリーを浸透させた。次に余分なスラリーを遠心分離器を利用し、振り切って１２０℃で５時間乾燥したのち、９００℃で２時間焼成した。
【００４５】
次に担持量が１．５ｗｔ％になるように調整したヘキサクロロ白金酸塩の水溶液に真空デシケーター内で、このハニカム構造体を含浸した後、真空デシケーター内を減圧してハニカム構造体内の気泡を取り除き、ハニカム構造体の内部までスラリーを浸透させた。次に余分なスラリーを遠心分離器を利用し、振り切って１２０℃で５時間乾燥したのち、６００℃で２時間焼成した（触媒フィルターＡとする）。
【００４６】
次に参考例６と同じ方法で所定の触媒を３次元網目構造体に触媒を付着させた（触媒フィルターＢとする）。
【００４７】
以上の触媒フィルターＡを排ガス流出口に、触媒フィルターＢを排ガス入口に設置して排ガス浄化装置を作製した。先に示した図２はこの参考例の排ガス浄化装置に対応する。
【００４８】
（参考例２５）
コージェライトの粉末（粒径：５μｍ）をこの粉末量に対して０．５ｗｔ％となるようにポリカルボン酸アンモニウム塩を溶解させた水溶液に投入した後、ボールミルにて１８時間解粒・混合して、スラリーを調製した。次にこのスラリーにウレタン製の発泡体を含浸させ、遠心分離器により余剰のスラリーを取り除いた後、１３８０℃で５時間焼成して１インチ当たりの内部連続空間の数が２０個である３次元網目構造体を作製した。次に３次元網目構造体の排ガス流入出面が図３に示すように排ガス流れに対して６０度傾いた形状に切り出して参考例２５の３次元網目状構造体を作製した。
【００４９】
（参考例２６、２７）
３次元網目構造体にゾル粒径が１０ｎｍ，１００ｎｍのＳｉＯ2ゾル溶液に含浸した後に、１２０℃で乾燥した後、９００℃で５時間焼成してＳｉＯ2コート３次元網目構造体を作製した。出発原料として硫酸セシウム、硝酸銅を３次元構造体に対して７ｗｔ％、モル比：Ｃｓ／Ｃｕ＝１／４となるように秤量して蒸留水に溶解させて水溶液を調製した後、前記３次元網目構造体を含浸した後、真空デシケーター内を減圧して３次元網目構造体内の気泡を取り除き、３次元網目構造体の内部までスラリーを浸透させた。次に余分なスラリーを遠心分離器を利用し、振り切って１２０℃で５時間乾燥したのち、９００℃で２時間焼成して触媒を付着した３次元網目構造体を作製した。
【００５０】
（実施例１、２）
３次元網目構造体にゾル粒径が１０ｎｍのＳｉＯ2ゾル溶液に粒径が１．５μｍのＳｉＯ2粒子をそれぞれ含浸した後に、１２０℃で乾燥した後、９００℃で５時間焼成してＳｉＯ2コート３次元構造体を作製した。出発原料として硫酸セシウム、硝酸銅を３次元構造体に対して７ｗｔ％、モル比：Ｃｓ／Ｃｕ＝１／４となるように秤量して蒸留水に溶解させて水溶液を調製した後、前記３次元網目構造体を含浸した後、真空デシケーター内を減圧して３次元網目構造体内の気泡を取り除き、３次元網目構造体の内部までスラリーを浸透させた。次に余分なスラリーを遠心分離器を利用し、振り切って１２０℃で５時間乾燥したのち、９００℃で２時間焼成して触媒を付着した３次元網目構造体を作製した。
【００５１】
（参考例２８）
３次元網目構造体にゾル粒径が１００ｎｍのＳｉＯ2ゾル溶液に含浸した後に、１２０℃で乾燥した後、９００℃で５時間焼成してＳｉＯ2コート３次元網目構造体を作製し、０．１％のＨＦに浸食させた後に、蒸留水で洗浄して、酸処理３次元網目構造体を作製した。次に出発原料として硫酸セシウム、硝酸銅を３次元構造体に対して７ｗｔ％、モル比：Ｃｓ／Ｃｕ＝１／４となるように秤量して蒸留水に溶解させて水溶液を調製した後、前記３次元網目構造体を含浸した後、真空デシケーター内を減圧して３次元網目構造体内の気泡を取り除き、３次元網目構造体の内部までスラリーを浸透させた。次に余分なスラリーを遠心分離器を利用し、振り切って１２０℃で５時間乾燥したのち、９００℃で２時間焼成して触媒を付着した３次元網目構造体を作製した。
【００５２】
（比較例１〜６）
硫酸セシウム、水酸化セシウム、炭酸セシウム、酢酸マンガン、酢酸コバルト、酢酸ランタン、酢酸鉄、硝酸銅、酸化硫酸バナジウムを用いた他は参考例６〜２０と同じ方法にて触媒フィルターを作製した。
【００５３】
（比較例７）
ヘキサクロロ白金酸塩を用いて担持量が１．５ｗｔ％になるように調整したヘキサクロロ白金酸塩の水溶液に真空デシケーター内で、このハニカム構造体を含浸した後、真空デシケーター内を減圧してハニカム構造体内の気泡を取り除き、ハニカム構造体の内部までスラリーを浸透させた。次に余分なスラリーを遠心分離器を利用し、振り切って１２０℃で５時間乾燥したのち、６００℃で２時間焼成して触媒担持フィルターを作製した。
【００５４】
以上のようにして作製した参考例１〜２２の排ガス浄化触媒、浄化触媒フィルターと比較例１〜７の排ガス浄化触媒、浄化触媒フィルターについて性能比較試験を行った。以下その結果について説明する。
【００５５】
（比較例１０、１１）
３次元網目構造体にゾル粒径が５ｎｍ，１６０ｎｍのＳｉＯ2ゾル溶液に含浸した後に、１２０℃で乾燥した後、９００℃で５時間焼成してＳｉＯ2コート３次元構造体を作製した。出発原料として硫酸セシウム、硝酸銅を３次元構造体に対して７ｗｔ％、モル比：Ｃｓ／Ｃｕ＝１／４となるように秤量して蒸留水に溶解させて水溶液を調製した後、前記３次元網目構造体を含浸した後、真空デシケーター内を減圧して３次元網目構造体内の気泡を取り除き、３次元網目構造体の内部までスラリーを浸透させた。次に余分なスラリーを遠心分離器を利用し、振り切って１２０℃で５時間乾燥したのち、９００℃で２時間焼成して触媒を付着した３次元網目構造体を作製した。
【００５６】
（比較例１２、１３）
３次元網目構造体にゾル粒径が１０ｎｍのＳｉＯ2ゾル溶液に粒径が０．５、９μｍのＳｉＯ2粒子をそれぞれ含浸した後に、１２０℃で乾燥した後、９００℃で５時間焼成してＳｉＯ2コート３次元構造体を作製した。出発原料として硫酸セシウム、硝酸銅を３次元構造体に対して７ｗｔ％、モル比：Ｃｓ／Ｃｕ＝１／４となるように秤量して蒸留水に溶解させて水溶液を調製した後、前記３次元網目構造体を含浸した後、真空デシケーター内を減圧して３次元網目構造体内の気泡を取り除き、３次元網目構造体の内部までスラリーを浸透させた。次に余分なスラリーを遠心分離器を利用し、振り切って１２０℃で５時間乾燥したのち、９００℃で２時間焼成して触媒を付着した３次元網目構造体を作製した。
【００５７】
（比較例９）
コージェライトの粉末（粒径：５μｍ）をこの粉末量に対して０．５ｗｔ％となるようにポリカルボン酸アンモニウム塩を溶解させた水溶液に投入した後、ボールミルにて１８時間解粒・混合して、スラリーを調製した。次にこのスラリーにウレタン製の発泡体を含浸させ、遠心分離器により余剰のスラリーを取り除いた後、１３８０℃で５時間焼成して１インチ当たりの内部連続空間の数が２０個である３次元網目構造体を作製して比較例９の３次元網目状構造体を作製した。
【００５８】
（評価例１）
（表１）の実施例１〜５に示す１平方インチ当たりの内部空間通気孔の個数を持つ３次元網目構造体へ台上エンジン（排気量：３０００ｃｃ）からの排ガスを導入し、３次元網目構造体の上流と下流での差圧を測定した。更に、触媒を付着させた前記３次元網目構造体に流入するパティキュレートの量と同構造体を通過後の排出パティキュレートの量及び同構造体に残存するパティキュレートの量から同構造体に付着させた触媒の作用によるパティキュレートの燃焼率を測定した。その結果を（表１）に示す。
【００５９】
（表１）から明らかなように、内部連続通気孔の増大に伴い差圧は上昇傾向にあり、実施例５の場合、差圧の上昇率が著しく大きい。一方内部連続通気孔の増大に伴い触媒とパティキュレートとの衝突回数が増大しパティキュレートの燃焼除去率も増大する。参考例１では差圧の上昇率は小さいが、付着触媒とパティキュレートとの接触回数が小さい。差圧の上昇率が小さく、パティキュレートの燃焼に有利な仕様としては内部連続通気孔が１５〜３０程度であることが判る。
【００６０】
（評価例２）
（表２）に示すように参考例６〜１８及び比較例１〜７のそれぞれの組成の触媒を付着させた３次元網目構造体へ台上エンジン（排気量：３０００ｃｃ）の排ガスを導入し、３次元網目構造体の上流と下流での差圧を測定した。更に、触媒を付着させた前記３次元網目構造体に流入するパティキュレートの量と同構造体を通過後の排出パティキュレートの量及び同構造体に残存するパティキュレートの量から同構造体に付着させた触媒の作用によるパティキュレートの燃焼率を測定した。１時間後及び３０時間後の燃焼率についての結果を（表２）に示す。
【００６１】
【表２】
（表２）から明らかなように、排ガスパティキュレートの燃焼率は、比較例１〜７の排ガス浄化触媒を用いた場合に比べ、参考例６〜２０における排ガス浄化触媒を用いた場合の方が初期の燃焼率が高く、また耐久性も高いことが判った。
【００６３】
（評価例３）
（表３）に示すように参考例６の組成のままのもの、参考例１９，２０及び比較例７の触媒に対してそれぞれコーティング耐熱材料を付着させた３次元網目構造体へ台上エンジン（排気量：３０００ｃｃ）の排ガスを導入し３次元網目構造体の上流と下流での差圧を測定した。更に、触媒を付着させた前記３次元網目構造体に流入するパティキュレートの量と同構造体を通過後の排出パティキュレートの量及び同構造体に残存するパティキュレートの量から同構造体に付着させた触媒の作用によるパティキュレートの燃焼率を測定した。さらにガスクロマトグラフを用いて触媒を付着させた３次元網目構造体通過前後の排ガス中の炭化水素の量を調べた。パティキュレート及び炭化水素の燃焼率の測定結果を（表３）に示す。
【００６４】
【表３】
（表３）から明らかなように、本発明に係る参考例６，１９，２０については比較例７に比べてパティキュレートの燃焼率が高く、また炭化水素の燃焼熱も高いことが判った。
【００６６】
（評価例４）
参考例２１，２２の触媒を付着させた３次元網目構造体を試料として、台上エンジン（排気量：３０００ｃｃ）の排ガスを導入し、３次元網目構造体の上流と下流での差圧を測定した。更に、触媒を付着させた前記３次元網目構造体に流入するパティキュレートの量と同構造体を通過後の排出パティキュレートの量及び同構造体に残存するパティキュレートの量から同構造体に付着させた触媒の作用によるパティキュレートの燃焼率を測定した。さらにガスクロマトグラフを用いて触媒を付着させた３次元網目構造体通過前後の排ガス中の炭化水素の量を調べた。この測定によるパティキュレート及び炭化水素の燃焼率のみについてその結果を（表４）に示す。
【００６７】
【表４】
（表４）から明らかなように、排ガスパティキュレートの燃焼率は、本発明の実施例における排ガス浄化触媒を用いた場合にパティキュレートの燃焼率が高く、また炭化水素の燃焼熱も高いことが判った。
【００６９】
（評価例５）
参考例２５と比較例９に示した内部空間通気孔を持つ３次元網目構造体へ台上エンジン（排気量：３０００ｃｃ）からの排ガスを導入し、３次元網目構造体の上流と下流での差圧を測定した。その結果を（表５）に示す。
【００７０】
【表５】
（表５）から明らかなように、同じ容積の場合、３次元構造体の排ガス流入出面が排ガス流れに対して垂直でない場合、垂直な場合に比べて排ガス差圧が低い事が判る。このように３次元構造体の排ガス流入出口が排ガス流れに対して垂直では無い場合、垂直な場合に比べて差圧が小さいために、排ガス流れ方向の長さを長くできる。３次元構造体の排ガス流れ方向の長さを長くすることにより、パティキュレートとの接触性を増す事が可能となり性能を向上させることができることが判る。
【００７２】
（評価例６）
（表６）に示すように参考例２６〜２８、実施例１、２及び比較例１０〜１３のそれぞれの組成の触媒を付着させた３次元網目構造体へ台上エンジン（排気量：３０００ｃｃ）の排ガスを導入し、３次元網目構造体の上流と下流での差圧を測定した。更に、触媒を付着させた前記３次元網目構造体に流入するパティキュレートの量と同構造体を通過後の排出パティキュレートの量及び同構造体に残存するパティキュレートの量から同構造体に付着させた触媒の作用によるパティキュレートの燃焼率を測定した。１時間後及び３０時間後の燃焼率についての結果を（表６）に示す。
【００７３】
【表６】
（表６）から明らかなように、排ガスパティキュレートの燃焼率は、比較例１０〜１３の排ガス浄化触媒を用いた場合に比べ、参考例２６〜２８、実施例１、２における排ガス浄化触媒を用いた場合の方が初期の燃焼率が高く、また耐久性も高いことが判った。
【００７５】
【発明の効果】
本発明によれば、３次元構造体に形成する材料が耐熱性無機材料のゾルと耐熱性無機材料の粉末からなり、前記耐熱性無機材料のゾルの粒子径が５ｎｍよりも大きく且つ１６０ｎｍよりも小さく、前記耐熱性無機材料の酸化物粒子の粒子径が０．５μｍよりも大きくて９μｍよりも小さいものとしたもので、３次元構造体の表面に凹凸の耐熱性無機材料部が得られる。これにより、混合する耐熱性無機材料の粒子が脱離することなく安定して３次元構造体表面に形成され、この上に付着させた触媒が３次元網目構造体との反応により劣化することを抑制でき、更に触媒とパティキュレートとの接触性が向上し、３次元構造体通過中に効率よく長時間安定してパティキュレートの燃焼が可能となる。
【図面の簡単な説明】
【図１】 本発明の実施の形態における排ガス浄化装置の構成を示す図
【図２】 排ガス浄化材の他の実施の形態を示す排ガス浄化装置の部分拡大図
【図３】 本発明の３次元網目構造体の形態を示す図
【符号の説明】
１ 排ガス入口
２ 排ガス出口
３ ３次元網目状構造体
４ ハニカム構造体
５ キャン
６ エンジン
７ 差圧計[0001]
BACKGROUND OF THE INVENTION
The present invention uses an exhaust gas purification material for removing particulate matter (particulates) such as hydrocarbons and combustible carbon fine particles contained in combustion engines such as diesel engines and industrial exhaust gas, and this exhaust gas purification material. The present invention relates to an exhaust gas purification device.
[0002]
[Prior art]
Particulates in exhaust gas from a diesel engine have a particle size of almost 1 micron or less, and are likely to float in the atmosphere and be easily taken into the human body by breathing. In addition, since it contains carcinogenic substances, it is expected that emission regulations will become stricter in the future.
[0003]
Conventionally, there are the following two methods for removing these particulate substances.
[0004]
(1) Use a heat-resistant gas filter such as a ceramic honeycomb, ceramic foam, or metal foam that is closed at one end to collect fine particles in the exhaust gas, and if the back pressure rises, burn the deposited fine particles with an electric heater or the like. How to play the filter.
[0005]
(2) A method in which fine particles are subjected to a combustion reaction by catalytic action using a catalyst, and combustion regeneration is performed at the temperature of the exhaust gas in the exhaust gas without using a heater or the like.
[0006]
However, in the method (1), the combustion temperature of the particulates is high, and a large amount of energy is required to burn and remove the collected particulates and regenerate the filter. Furthermore, the filter burns and cracks due to combustion in the high temperature range and the reaction heat. In addition, since a special device is required, there is a problem of an increase in size and cost as a purification device.
[0007]
On the other hand, since the method (2) burns and removes by the action of the catalyst in the exhaust gas treatment temperature range, it becomes a purification device that is reduced in size and cost without requiring a special device, but can be purified in the entire exhaust gas temperature range. No catalyst has been developed.
[0008]
[Problems to be solved by the invention]
The heat-resistant structure that supports the catalyst is one of the honeycomb structures generally used in gasoline vehicles or one end of each cell of the honeycomb structure for the purpose of collecting particulates. There is a closed honeycomb filter.
[0009]
However, in the honeycomb structure, the exhaust gas passage is linear, and the solid particulates passing through the passage at a speed of several meters to several tens of meters or more are in the vertical direction of the exhaust gas flow (in the honeycomb wall direction). The velocity component of is significantly smaller than that of gas molecules. Therefore, it is difficult to come into contact with the catalyst coated on the passage wall, and the purification reaction hardly occurs. On the other hand, in the honeycomb structure for the purpose of collecting one end closed with one end of the cell closed, the particulates are filtered and collected from the exhaust gas by the wall surface constituting the cell passage. For this reason, the contact property with the catalyst coated on the wall surface is good.
[0010]
However, in this case, if the operation in a low exhaust gas temperature range where the activity of the catalyst does not sufficiently act continues, the particulates are not completely purified, and the amount of particulates deposited on the cell wall increases, resulting in a large back pressure. The problem that it cannot be used for a long time occurs.
[0011]
The present invention is excellent in flammability with respect to particulates from diesel engines, and the exhaust gas temperature is extremely low such as low load and low rotation, and particulates are deposited on the filter even in a low temperature range where the catalytic action is not sufficiently exhibited. It is an object of the present invention to provide an exhaust gas purifying material that can be used stably for a long time without causing a pressure loss due to the above, and an exhaust gas purifying apparatus using the same.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a material that is formed on a three-dimensional structure with heat resistance so that an uneven heat-resistant inorganic material portion is obtained on the surface of the three-dimensional network structure having internal continuous air holes. It consists of a sol of an inorganic material and a powder of a heat resistant inorganic material, the particle diameter of the sol of the heat resistant inorganic material is larger than 5 nm and smaller than 160 nm, and the particle size of the oxide particles of the heat resistant inorganic material is 0. It is larger than 5 μm and smaller than 9 μm, and an uneven heat-resistant inorganic material part is obtained on the surface of the three-dimensional structure. As a result, the particles of the heat-resistant inorganic material to be mixed are stably formed on the surface of the three-dimensional structure without detachment, and the catalyst deposited thereon deteriorates due to the reaction with the three-dimensional network structure. Further, the contact property between the catalyst and the particulates can be improved, and the particulates can be efficiently burned while passing through the three-dimensional structure.
[0013]
3The dimensional network structure has a continuous ventilation space in the structure, and the number of the spaces is 5 to 30, preferably 10 to 20, per square inch. More preferably, the perpendicular to the exhaust gas inflow / outflow surface of the three-dimensional network structure forms an acute angle or an obtuse angle with respect to the exhaust gas flow direction. Further, the honeycomb structure has 200 to 500 per square inch. As a material of the three-dimensional network structure or honeycomb structure, cordierite (2MgO · 5SiO2・ 2Al2OThree), Mullite (Al2OThree・ 3SiO2), Alumina (Al2OThree), Silica (SiO2), Titania (TiO2), Zirconia (ZrO2), Ceramics such as silica-alumina, alumina-zirconia, alumina-titania, silica-titania, silica-zirconia, titania-zirconia, and metal materials such as SUS301S, Inconel (Inconel X, Inconel W, etc.) It is not limited to this.
[0014]
Further, an inorganic coat layer is formed on the three-dimensional network structure or honeycomb structure. The inorganic coating layer is a porous body having a high specific surface area that is coated on a three-dimensional network structure. As the material for the inorganic coat layer, ceramics such as alumina, silica, titania, zirconia, silica-alumina, alumina-zirconia, and alumina-titania are preferably used, but are not limited thereto.
[0015]
Examples of the method for supporting the inorganic coat layer on the three-dimensional network structure or honeycomb structure include a sol-gel method and a slurry method.
[0016]
The sol-gel method is a method in which an acid (hydrochloric acid, acetic acid, etc.) is added to a solution containing an organic salt (alkoxide, etc.) of a metal element constituting the inorganic coat layer to adjust the pH of the solution, and then the three-dimensional structure is added to the solution. A solution containing a metal element constituting an inorganic coating layer is impregnated by impregnating the body or honeycomb structure, and then the solution coated on the three-dimensional network structure or honeycomb structure is brought into contact with water vapor to form a sol by hydrolysis reaction. And then, after further gelation, firing.
[0017]
In the slurry method, the raw material powder of the inorganic coating layer is put into an aqueous solution in which a dispersant (polycarboxylate, etc.) is dissolved in advance, and the raw material powder in this aqueous solution is pulverized and mixed with a ball mill or the like. After the slurry is prepared by the above method, the slurry is impregnated with a three-dimensional network structure or a honeycomb structure and coated with the slurry, followed by firing. Although these are mentioned as a general method of carrying | supporting, it is not limited to this.
[0018]
However, the inorganic part formed in the three-dimensional network structure is ZrO.2And TiO2, SiO2In particular, SiO2The sol is preferably a sol, and the particle diameter of the sol is preferably larger than 5 nm and smaller than 160 nm.. ThisA heat-resistant powder is mixed with the sol, and the powder preferably has a particle size larger than 0.5 μm and smaller than 9 μm.
[0019]
As catalyst materials to be attached to these structures, the group consisting of a salt of a group 1a element, a group 5a element and a group 1b element according to the IUPAC classification, a salt of a group 1a element, a group 5a element, a group 1b element and a group 6a And those composed of at least one of the 7a group and the 8a group.
[0020]
The catalyst is prepared by the following method. That is, oxides, hydroxides, carbonates, acetates, nitrates, oxalates, chlorides, and the like of each constituent element are mixed at a predetermined ratio. As a method of mixing, after mixing each material in a solid state, after preparing a mixed aqueous solution of each metal salt, evaporating the solvent and solidifying the metal salt, after preparing a mixed aqueous solution of each metal salt, Method of hydrolysis by adding ammonia water, etc. After preparing a mixed aqueous solution of each metal salt, add appropriate amount of polyvalent organic carboxylic acid such as citric acid and malic acid, evaporate solvent or adjust pH of solution The method of solidifying by doing can be used. A predetermined catalyst is obtained by calcining the mixture thus prepared. Moreover, it is also possible to produce each constituent element of the catalyst separately by the same method as described above.
[0021]
With this configuration, the catalyst is sufficiently kept in contact with the discharged particulate, and the particulate purification reaction proceeds by the highly active catalyst.
[0022]
When the exhaust gas temperature is extremely low, a part of the exhausted particulate is burned by the action of the catalyst, and the unburned particulate is discharged out of the system. As a result, particulates do not accumulate in the filter and the differential pressure does not rise even in the exhaust gas temperature range where the particulates cannot be burned and removed 100% by the action of the catalyst, and the particulates can be burnt and removed continuously and stably. Become.
[0023]
Further, on the exhaust gas inlet side of the inorganic structure, a catalyst comprising a group 1a element salt and a group 5a element and a group 1b element according to the IUPAC classification, or a salt of the group 1a element, a group 5a element, a group 1b element and a group 6a, It is possible to purify CO and HC in addition to particulates by adopting a structure in which a catalyst consisting of at least one of the 7a group and 8a group is adhered, and a platinum group is adhered to the exhaust gas outlet side. Become.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Of the present inventionClaimDescribed in 1The invention ofThe material to be formed in the three-dimensional structure is composed of a heat-resistant inorganic material sol and a heat-resistant inorganic material powder,The particle diameter of the heat-resistant inorganic material mixed with the sol of the heat-resistant inorganic material having a particle diameter larger than 5 nm and smaller than 160 nm is larger than 0.5 μm and smaller than 9 μm.An uneven heat-resistant inorganic material part is obtained on the surface of the three-dimensional structure,The particles of the heat-resistant inorganic material to be mixed are stably formed on the surface of the three-dimensional structure without desorption. As a result, it is possible to suppress the catalyst deposited thereon from deteriorating due to the reaction with the three-dimensional network structure, and further, the contact property between the catalyst and the particulates is improved and the catalyst is efficiently passed while passing through the three-dimensional structure. The particulates can be burned stably over time.
[0025]
Claim2In the present invention, the heat-resistant inorganic oxide formed on the surface of the three-dimensional structure is SiO.2It is what is. As a result, it is possible to suppress the catalyst formed thereon from deteriorating due to the reaction with the three-dimensional network structure, further improving the contact between the catalyst and the particulates, and efficiently passing the three-dimensional structure for a long time. It is possible to burn particulates stably.
[0026]
Claim3The invention of claimDescribed in 1 or 2In the exhaust gas purifying material of the present invention, the three-dimensional network structure is the three-dimensional structure according to the invention of claim 22, the initial differential pressure is small, particulate deposition does not become a problem, and the efficiency is improved while passing through the structure. It has the effect that the particulate can be burned stably for a long time.
[0027]
Claim4The invention of claim1 to 3The exhaust gas purifying material according to any one of the above, a container for storing the exhaust gas purifying material, an exhaust gas inlet formed in a part of the container, and an exhaust gas inlet formed on the other side of the container. The exhaust gas purifying apparatus is provided and has an effect that a purifying apparatus having a simple apparatus configuration and excellent exhaust gas purifying characteristics can be obtained.
[0028]
Claim5The invention of claim4In the purification apparatus according to
[0029]
Claim6The invention of claim5In the invention, the container is disposed close to the engine manifold, and the catalytic activity can be improved by preventing a decrease in temperature at which exhaust gas from the engine combustion section flows into the catalyst section. Have.
[0030]
Hereinafter, the exhaust gas purifying material in the embodiment of the present invention will be described. FIG. 1 is a diagram showing a configuration of an exhaust gas purification apparatus in an embodiment of the present invention, and FIG. 2 is a partially enlarged view of the exhaust gas purification apparatus showing another embodiment of the exhaust gas purification material. FIG. 3 is a view showing the form of the three-dimensional network structure of the present invention.
[0031]
In FIG. 1, a
[0032]
1 and 2, the three-
[0033]
In FIG. 3, the perpendicular to the exhaust gas inflow / outflow surface of the three-dimensional structure forms an acute angle or an obtuse angle with respect to the exhaust gas flow direction.
[0034]
【Example】
(referenceExamples 1-5)
Cordierite powder (particle size: 5 μm) is poured into an aqueous solution in which polycarboxylic acid ammonium salt is dissolved so as to be 0.5 wt% with respect to the amount of the powder, and then pulverized and mixed in a ball mill for 18 hours. A slurry was prepared. Next, this slurry is impregnated with urethane foams having different densities and pore diameters, excess slurry is removed by a centrifuge, and then fired at 1380 ° C. for 5 hours to have the characteristics shown in (Table 1).referenceAs Examples 1 to 5, three-dimensional network structures were prepared.
[0035]
[Table 1]
In addition, after preparing cesium sulfate and copper nitrate as starting materials to 7 wt% with respect to the three-dimensional structure, molar ratio: Cs / Cu = 1/4 and dissolving in distilled water to prepare an aqueous solution, After impregnating the three-dimensional network structure, the inside of the vacuum desiccator was decompressed to remove bubbles in the three-dimensional network structure, and the slurry was infiltrated into the three-dimensional network structure. Next, excess slurry was shaken off using a centrifugal separator, dried at 120 ° C. for 5 hours, and then calcined at 900 ° C. for 2 hours to prepare a three-dimensional network structure to which the catalyst was attached.
[0037]
(referenceExamples 6-18)
As a starting material, cesium sulfate is used as a group 1a element and copper nitrate, vanadium oxide sulfate, chromium nitrate, manganese acetate, iron acetate, cobalt acetate, nickel acetate, 7 ammonium molybdate tetrahydrate,
[0038]
(referenceExamples 19-20)
SiO2, Γ-Al2OThreeAluminum isopropoxide used as an adhesive in an aqueous solution in which 0.5 wt% of a polycarboxylic acid ammonium salt is dissolved in a powder and is weighed to 15 wt% with respect to the three-dimensional network structure. Each of these powders was added and then pulverized and mixed in a ball mill for 18 hours to prepare a slurry.
[0039]
Next, after impregnating the obtained slurry with a three-dimensional network structure in a vacuum desiccator, the inside of the vacuum desiccator is decompressed to remove bubbles in the three-dimensional network structure, and the slurry is brought into the three-dimensional network structure. Infiltrated. Next, excess slurry was shaken off using a centrifugal separator, dried at 120 ° C. for 5 hours, and then calcined at 900 ° C. for 2 hours. nextreferenceA predetermined catalyst was supported in the same manner as in Example 6.
[0040]
(referenceExample 21)
γ-Al2OThreeIn addition, aluminum isopropoxide was added as an adhesive to an aqueous solution in which polycarboxylic acid ammonium salt was dissolved to 0.5 wt% with respect to this powder, and then obtained in a vacuum desiccator. After impregnating the slurry with the three-dimensional network structure, the inside of the vacuum desiccator was decompressed to remove bubbles in the three-dimensional network structure, and the slurry was infiltrated into the three-dimensional network structure. Next, excess slurry was shaken off using a centrifugal separator, dried at 120 ° C. for 5 hours, and then calcined at 900 ° C. for 2 hours.
[0041]
nextreferenceA predetermined catalyst slurry is prepared in the same manner as in Example 6, and one side of the three-dimensional network structure is impregnated. The impregnated three-dimensional network structure was set so as to be outside the rotation of the centrifuge and rotated to remove excess catalyst slurry and calcined at 900 ° C. for 2 hours.
[0042]
Next, the side where the catalyst is not adhered is γ-Al2OThreeA catalyst adhering filter was prepared by impregnating and drying a solution in which hexachloroplatinic acid was dissolved so as to be 1.5 wt%, followed by baking at 600 ° C. for 3 hours.
[0043]
(referenceExample 22)
γ-Al2OThreeThe aluminum isopropoxide used as an adhesive and these powders were respectively added to an aqueous solution in which polycarboxylic acid ammonium salt was dissolved to 0.5 wt% with respect to this powder. The mixture was pulverized and mixed for 18 hours to prepare a slurry.
[0044]
Next, after the obtained slurry was impregnated with the honeycomb structure in a vacuum desiccator, the inside of the vacuum desiccator was decompressed to remove bubbles in the honeycomb structure, and the slurry was infiltrated into the inside of the honeycomb structure. Next, excess slurry was shaken off using a centrifugal separator, dried at 120 ° C. for 5 hours, and then calcined at 900 ° C. for 2 hours.
[0045]
Next, this honeycomb structure is impregnated in an aqueous solution of hexachloroplatinate adjusted to 1.5 wt% in a vacuum desiccator, and then the inside of the vacuum desiccator is decompressed to remove bubbles in the honeycomb structure. The slurry was infiltrated into the inside of the honeycomb structure. Next, the excess slurry was shaken off using a centrifugal separator, dried at 120 ° C. for 5 hours, and then calcined at 600 ° C. for 2 hours (referred to as catalyst filter A).
[0046]
nextreferenceIn the same manner as in Example 6, a predetermined catalyst was adhered to a three-dimensional network structure (referred to as catalyst filter B).
[0047]
The above catalyst filter A was installed at the exhaust gas outlet and the catalyst filter B was installed at the exhaust gas inlet to produce an exhaust gas purification device. Figure 2 shown above shows thisreferenceCorresponds to the example exhaust gas purification device.
[0048]
(referenceExample 25)
Cordierite powder (particle size: 5 μm) is poured into an aqueous solution in which polycarboxylic acid ammonium salt is dissolved so as to be 0.5 wt% with respect to the amount of the powder, and then pulverized and mixed in a ball mill for 18 hours. A slurry was prepared. Next, this slurry is impregnated with urethane foam, and after removing excess slurry with a centrifuge, the slurry is fired at 1380 ° C. for 5 hours, and the number of internal continuous spaces per inch is 20 three-dimensional. A network structure was produced. Next, the exhaust gas inflow / outflow surface of the three-dimensional network structure is cut into a shape inclined by 60 degrees with respect to the exhaust gas flow as shown in FIG.referenceThe three-dimensional network structure of Example 25 was produced.
[0049]
(referenceExample 26, 27)
SiO having a sol particle size of 10 nm and 100 nm on a three-dimensional network structure2After impregnating the sol solution, it is dried at 120 ° C. and then calcined at 900 ° C. for 5 hours.2A coated three-dimensional network structure was produced. After preparing cesium sulfate and copper nitrate as starting materials at 7 wt% with respect to the three-dimensional structure and a molar ratio: Cs / Cu = 1/4 and dissolving in distilled water, an aqueous solution was prepared. After impregnating the three-dimensional network structure, the inside of the vacuum desiccator was decompressed to remove bubbles in the three-dimensional network structure, and the slurry was infiltrated into the three-dimensional network structure. Next, excess slurry was shaken off using a centrifugal separator, dried at 120 ° C. for 5 hours, and then calcined at 900 ° C. for 2 hours to prepare a three-dimensional network structure to which the catalyst was attached.
[0050]
(Example1, 2)
SiO having a sol particle size of 10 nm on a three-dimensional network structure2SiO having a particle size of 1.5 μm in the sol solution2After impregnating each of the particles, drying at 120 ° C., followed by firing at 900 ° C. for 5 hours, SiO 22A coated three-dimensional structure was produced. After preparing cesium sulfate and copper nitrate as starting materials at 7 wt% with respect to the three-dimensional structure and a molar ratio: Cs / Cu = 1/4 and dissolving in distilled water, an aqueous solution was prepared. After impregnating the three-dimensional network structure, the inside of the vacuum desiccator was decompressed to remove bubbles in the three-dimensional network structure, and the slurry was infiltrated into the three-dimensional network structure. Next, excess slurry was shaken off using a centrifugal separator, dried at 120 ° C. for 5 hours, and then calcined at 900 ° C. for 2 hours to prepare a three-dimensional network structure to which the catalyst was attached.
[0051]
(referenceExample28)
SiO having a sol particle size of 100 nm on a three-dimensional network structure2After impregnating the sol solution, it is dried at 120 ° C. and then calcined at 900 ° C. for 5 hours.2A coated three-dimensional network structure was prepared, eroded in 0.1% HF, and then washed with distilled water to prepare an acid-treated three-dimensional network structure. Next, after preparing cesium sulfate and copper nitrate as starting materials to 7 wt% with respect to the three-dimensional structure, molar ratio: Cs / Cu = 1/4 and dissolving in distilled water to prepare an aqueous solution, After impregnating the three-dimensional network structure, the inside of the vacuum desiccator was decompressed to remove bubbles in the three-dimensional network structure, and the slurry was infiltrated into the three-dimensional network structure. Next, excess slurry was shaken off using a centrifugal separator, dried at 120 ° C. for 5 hours, and then calcined at 900 ° C. for 2 hours to prepare a three-dimensional network structure to which the catalyst was attached.
[0052]
(Comparative Examples 1-6)
Other than using cesium sulfate, cesium hydroxide, cesium carbonate, manganese acetate, cobalt acetate, lanthanum acetate, iron acetate, copper nitrate, vanadium oxidereferenceCatalyst filters were prepared in the same manner as in Examples 6-20.
[0053]
(Comparative Example 7)
The honeycomb structure was impregnated with an aqueous solution of hexachloroplatinate adjusted to 1.5 wt% using hexachloroplatinate in a vacuum desiccator, and then the inside of the vacuum desiccator was decompressed to form a honeycomb structure. Bubbles in the body were removed, and the slurry was infiltrated into the honeycomb structure. Next, excess slurry was shaken off using a centrifugal separator, dried at 120 ° C. for 5 hours, and then calcined at 600 ° C. for 2 hours to prepare a catalyst-carrying filter.
[0054]
Produced as abovereferencePerformance comparison tests were conducted on the exhaust gas purification catalyst and purification catalyst filter of Examples 1 to 22 and the exhaust gas purification catalyst and purification catalyst filter of Comparative Examples 1 to 7. The results will be described below.
[0055]
(Comparative Examples 10 and 11)
3D network structure with sol particle size of 5nm, 160nm SiO2After impregnating the sol solution, it is dried at 120 ° C. and then calcined at 900 ° C. for 5 hours.2A coated three-dimensional structure was produced. After preparing cesium sulfate and copper nitrate as starting materials at 7 wt% with respect to the three-dimensional structure and a molar ratio: Cs / Cu = 1/4 and dissolving in distilled water, an aqueous solution was prepared. After impregnating the three-dimensional network structure, the inside of the vacuum desiccator was decompressed to remove bubbles in the three-dimensional network structure, and the slurry was infiltrated into the three-dimensional network structure. Next, excess slurry was shaken off using a centrifugal separator, dried at 120 ° C. for 5 hours, and then calcined at 900 ° C. for 2 hours to prepare a three-dimensional network structure to which the catalyst was attached.
[0056]
(Comparative Examples 12 and 13)
SiO having a sol particle size of 10 nm on a three-dimensional network structure2SiO having a particle size of 0.5, 9 μm in the sol solution2After impregnating each of the particles, drying at 120 ° C., followed by firing at 900 ° C. for 5 hours, SiO 22A coated three-dimensional structure was produced. After preparing cesium sulfate and copper nitrate as starting materials at 7 wt% with respect to the three-dimensional structure and a molar ratio: Cs / Cu = 1/4 and dissolving in distilled water, an aqueous solution was prepared. After impregnating the three-dimensional network structure, the inside of the vacuum desiccator was decompressed to remove bubbles in the three-dimensional network structure, and the slurry was infiltrated into the three-dimensional network structure. Next, excess slurry was shaken off using a centrifugal separator, dried at 120 ° C. for 5 hours, and then calcined at 900 ° C. for 2 hours to prepare a three-dimensional network structure to which the catalyst was attached.
[0057]
(Comparative Example 9)
Cordierite powder (particle size: 5 μm) is poured into an aqueous solution in which polycarboxylic acid ammonium salt is dissolved so as to be 0.5 wt% with respect to the amount of the powder, and then pulverized and mixed in a ball mill for 18 hours. A slurry was prepared. Next, this slurry is impregnated with urethane foam, and after removing excess slurry with a centrifuge, the slurry is fired at 1380 ° C. for 5 hours, and the number of internal continuous spaces per inch is 20 three-dimensional. A network structure was produced to produce a three-dimensional network structure of Comparative Example 9.
[0058]
(Evaluation example 1)
Exhaust gas from a table engine (displacement: 3000 cc) was introduced into the three-dimensional network structure having the number of internal space vents per square inch shown in Examples 1 to 5 of Table 1 to provide a three-dimensional network. The differential pressure upstream and downstream of the structure was measured. Further, the amount of the particulate flowing into the three-dimensional network structure to which the catalyst is adhered, the amount of the exhausted particulate after passing through the structure, and the amount of the particulate remaining in the structure are attached to the structure. The burning rate of the particulates due to the action of the catalyst was measured. The results are shown in (Table 1).
[0059]
As is clear from Table 1, the differential pressure tends to increase with the increase of the internal continuous vent, and in the case of Example 5, the increase rate of the differential pressure is remarkably large. On the other hand, as the number of internal continuous vents increases, the number of collisions between the catalyst and the particulates increases, and the particulate removal rate also increases.referenceIn Example 1, the increase rate of the differential pressure is small, but the number of contact between the adhesion catalyst and the particulate is small. It can be seen that the internal continuous air vent is about 15 to 30 as a specification that has a small differential pressure increase rate and is advantageous for particulate combustion.
[0060]
(Evaluation example 2)
As shown in (Table 2)referenceExhaust gas from a bench engine (displacement: 3000 cc) was introduced into the three-dimensional network structure to which the catalysts having the compositions of Examples 6 to 18 and Comparative Examples 1 to 7 were attached, and upstream and downstream of the three-dimensional network structure. The differential pressure at was measured. Further, the amount of the particulate flowing into the three-dimensional network structure to which the catalyst is adhered, the amount of the exhausted particulate after passing through the structure, and the amount of the particulate remaining in the structure are attached to the structure. The burning rate of the particulates due to the action of the catalyst was measured. The results for the burning rate after 1 hour and after 30 hours are shown in Table 2.
[0061]
[Table 2]
As apparent from (Table 2), the combustion rate of the exhaust gas particulates is higher than that when the exhaust gas purification catalysts of Comparative Examples 1 to 7 are used.referenceIt was found that the initial combustion rate was higher and the durability was higher when the exhaust gas purification catalyst in Examples 6 to 20 was used.
[0063]
(Evaluation example 3)
As shown in (Table 3)referenceAs in the composition of Example 6,referenceExhaust gas from a bench engine (displacement: 3000 cc) was introduced into a three-dimensional network structure in which a coating heat-resistant material was adhered to the catalysts of Examples 19 and 20 and Comparative Example 7, respectively, upstream and downstream of the three-dimensional network structure. The differential pressure at was measured. Further, the amount of the particulate flowing into the three-dimensional network structure to which the catalyst is adhered, the amount of the exhausted particulate after passing through the structure, and the amount of the particulate remaining in the structure are attached to the structure. The burning rate of the particulates due to the action of the catalyst was measured. Furthermore, the amount of hydrocarbons in the exhaust gas before and after passing through the three-dimensional network structure to which the catalyst was attached was examined using a gas chromatograph. The measurement results of the burning rate of particulates and hydrocarbons are shown in (Table 3).
[0064]
[Table 3]
As is clear from (Table 3), according to the present invention.referenceIn Examples 6, 19, and 20, it was found that the combustion rate of the particulates was higher than that of Comparative Example 7, and the combustion heat of the hydrocarbons was also higher.
[0066]
(Evaluation example 4)
referenceExhaust gas from a bench engine (displacement: 3000 cc) was introduced using the three-dimensional network structure to which the catalyst of Examples 21 and 22 was attached as a sample, and the differential pressure between the upstream and downstream of the three-dimensional network structure was measured. . Further, the amount of the particulate flowing into the three-dimensional network structure to which the catalyst is adhered, the amount of the exhausted particulate after passing through the structure, and the amount of the particulate remaining in the structure are attached to the structure. The burning rate of the particulates due to the action of the catalyst was measured. Furthermore, the amount of hydrocarbons in the exhaust gas before and after passing through the three-dimensional network structure to which the catalyst was attached was examined using a gas chromatograph. The results of only the particulates and hydrocarbon combustion rates obtained by this measurement are shown in Table 4.
[0067]
[Table 4]
As is clear from (Table 4), the combustion rate of exhaust gas particulates is high when the exhaust gas purification catalyst in the embodiment of the present invention is used, and the combustion heat of hydrocarbons is also high. understood.
[0069]
(Evaluation example 5)
referenceExhaust gas from a bench engine (displacement: 3000 cc) is introduced into the three-dimensional network structure having internal space vents shown in Example 25 and Comparative Example 9, and the differential pressure between the upstream and downstream of the three-dimensional network structure Was measured. The results are shown in (Table 5).
[0070]
[Table 5]
As can be seen from Table 5, when the volume is the same, the exhaust gas differential pressure is lower when the exhaust gas inflow / outflow surface of the three-dimensional structure is not perpendicular to the exhaust gas flow than when it is perpendicular. Thus, when the exhaust gas inlet / outlet of the three-dimensional structure is not perpendicular to the exhaust gas flow, the length in the exhaust gas flow direction can be increased because the differential pressure is smaller than in the vertical case. It can be seen that by increasing the length of the three-dimensional structure in the exhaust gas flow direction, the contact property with the particulates can be increased and the performance can be improved.
[0072]
(Evaluation example 6)
As shown in (Table 6)referenceExample 26 ~28, Examples 1 and 2And the exhaust gas of the bench engine (displacement: 3000 cc) is introduced into the three-dimensional network structure to which the catalysts of the compositions of Comparative Examples 10 to 13 are attached, and the differential pressure between the upstream and downstream of the three-dimensional network structure Was measured. Further, the amount of the particulate flowing into the three-dimensional network structure to which the catalyst is adhered, the amount of the exhausted particulate after passing through the structure, and the amount of the particulate remaining in the structure are attached to the structure. The burning rate of the particulates due to the action of the catalyst was measured. The results for the burning rate after 1 hour and after 30 hours are shown in Table 6.
[0073]
[Table 6]
As is clear from (Table 6), the combustion rate of the exhaust gas particulates is higher than that when the exhaust gas purification catalysts of Comparative Examples 10 to 13 are used.referenceExample 26 ~28, Examples 1 and 2It was found that the initial combustion rate was higher and the durability was higher when the exhaust gas purifying catalyst was used.
[0075]
【The invention's effect】
According to the present invention,The material to be formed in the three-dimensional structure is composed of a sol of a heat resistant inorganic material and a powder of a heat resistant inorganic material, and the particle diameter of the sol of the heat resistant inorganic material is larger than 5 nm and smaller than 160 nm. The particle diameter of the oxide particles of the material is larger than 0.5 μm and smaller than 9 μm, and an uneven heat-resistant inorganic material part is obtained on the surface of the three-dimensional structure. As a result, the particles of the heat-resistant inorganic material to be mixed are stably formed on the surface of the three-dimensional structure without detachment, and the catalyst deposited thereon deteriorates due to the reaction with the three-dimensional network structure. Further, the contact between the catalyst and the particulates can be improved, and the particulates can be burned efficiently and stably for a long time while passing through the three-dimensional structure.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an exhaust gas purifying apparatus according to an embodiment of the present invention.
FIG. 2 is a partially enlarged view of an exhaust gas purifying apparatus showing another embodiment of the exhaust gas purifying material.
FIG. 3 is a diagram showing a form of a three-dimensional network structure according to the present invention.
[Explanation of symbols]
1 Exhaust gas inlet
2 Exhaust gas outlet
3 3D network structure
4 Honeycomb structure
5 Can
6 Engine
7 Differential pressure gauge
Claims (6)
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| JP11044298A JP3823528B2 (en) | 1997-10-27 | 1998-04-21 | Exhaust gas purification material and exhaust gas purification apparatus using the same |
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| JP29388297 | 1997-10-27 | ||
| JP9-293882 | 1997-10-27 | ||
| JP11044298A JP3823528B2 (en) | 1997-10-27 | 1998-04-21 | Exhaust gas purification material and exhaust gas purification apparatus using the same |
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| JP3823528B2 true JP3823528B2 (en) | 2006-09-20 |
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| JP4887550B2 (en) * | 2000-04-11 | 2012-02-29 | パナソニック株式会社 | Exhaust gas purification material |
| JP4639455B2 (en) * | 2000-10-02 | 2011-02-23 | パナソニック株式会社 | Exhaust gas purification material |
| JP2002174111A (en) * | 2000-12-07 | 2002-06-21 | Matsushita Electric Ind Co Ltd | Exhaust gas purifying material |
| JP4852805B2 (en) * | 2001-07-23 | 2012-01-11 | パナソニック株式会社 | Exhaust gas purification catalyst and exhaust gas purification catalyst filter using the same |
| US20120122663A1 (en) * | 2007-08-27 | 2012-05-17 | Tokyo Roki Co. Ltd. | Process for producing catalyst for exhaust gas purification and catalyst for exhaust gas purification |
| JP6652313B2 (en) * | 2015-01-08 | 2020-02-19 | 東京窯業株式会社 | Arrangement structure of honeycomb structure |
| JP6893779B2 (en) * | 2016-12-14 | 2021-06-23 | エヌ・イーケムキャット株式会社 | Method for Producing Inorganic Oxide Particle-Supported Structure Carrier |
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